A solar cell, or photovoltaic cell, is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon.[1] It is a form of photoelectric cell, defined as a device whose electrical characteristics, such as current, voltage, or resistance, vary when exposed to light. Solar cells are the building blocks of photovoltaic modules, otherwise known as solar panels.
The operation of a photovoltaic (PV) cell requires 3 basic attributes:
The absorption of light, generating either electron-hole pairs or excitons.
The separation of charge carriers of opposite types.
The separate extraction of those carriers to an external circuit.
Construction-
It essentially consists of a silicon PN junction diode with a glass window on top surface layer of P material is made extremely thin so, that incident light photon’s may easily reach the PN junction.
Working of solar cell
1) Solar cell works under the principle of photovoltaic effect-when light is incident on ‘P-N’ junction a potential gets developed across the junction, this potential is capable of driving a current through the circuit.
2) Hence light energy is getting converted to electrical energy.
3) Here electrons absorbs photons having energy greater than the band gap energy hence they can make transition from the valence band to the conduction band & hence contributes current.
4) The wavelength of light is given by the relation, $E_g = h = hc/λ =1.24$
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